The invention relates to a filter, in particular for the lubricating oil of an internal combustion engine.
Such a filter is, for example, known from DE 41 39 680. This filter has according to FIG. 1 of the publication, an annular filter cartridge which is pushed onto a central tube with the assistance of gaskets 18, 19. The central tube is connected fast with a bell housing 11, by means of which a simplification of the structural assembly can be achieved in a high degree of economy. The bell housing is attached, for example to a motor block, by means of an adapter 15. By using different adapters, a flexible utilization of the filter with different sizes of connectors is possible.
However, the disclosed structure also has disadvantages. As a result of the use of the adapter, it becomes necessary to incur an additional sealing expense in the form of gasket rings 14, 24. Also, the gaskets, which are used for sealing the filter cartridge, have a complex structure, so that no standard parts can be used.
The invention therefore is addressed to the object of providing a filter, especially for lubricant oil of an internal combustion engine, which will consist of few parts and thus will be easy to service as well as inexpensive. This object is achieved by the invention as described and claimed hereinafter.
The substantial advantage of the invention is to be seen in the fact that the filter in the basic version consists of four component parts, namely a housing, a center tube, a metal-free cartridge and a gasket. In a preferred manner the housing is an injection molded synthetic resin part. This part is very inexpensive to manufacture and can also be made, for example, from recycled material.
The filter is provided with a replaceable filter element. The filter element is merely pushed over the supporting tube and has a radial gasket.
The entire housing is open toward a flange. This means that no end plate closing the pot-shaped housing is necessary. By the elimination of the end plate, direct access to the filter element is assured, so that it can be replaced without special tools.
In one embodiment of the invention provision is made for the support tube to be threaded into the housing or, when injection molded plastic is used, for it to be welded by ultrasound or high frequency or adhesively joined.
The filter element in one embodiment of the invention is provided with end plates which are made of nitrile rubber and thus have a high elasticity. In this way additional sealing means can be omitted. The end plates themselves produce a radial sealing of the filter element. In a preferred embodiment a filter element bypass valve can be arranged on the supporting tube. The possibility also exists for arranging a non-return valve in the supporting tube. Both valves are of simple construction and consist substantially of a valve spring and a valve plate.
Usually the filter element is mounted floatingly on the support tube, i.e. its axial position is defined by the abutment on the bottom of the housing. For precise fixation of the filter element, a catch element can be provided on the support tube, which prevents displacement of the filter element. It is also possible to provide a sleeve or the like on the support tube for the fixation of the filter element.
To prevent raw oil, i.e. oil that has not yet been filtered, from flowing in reverse direction, the end plate facing the flange can be equipped with a non-return valve, for example in the form of a one-piece profile gasket. In this way the filter is effectively prevented from running empty.
These and additional features of preferred embodiments of the invention will be found not only in the claims but also in the description and the drawings, and the individual features can each be realized individually or together in the form of subcombinations in the embodiments of the invention and in other fields, and can constitute advantageous as well as independently patentable embodiments, for which protection is hereby claimed.